1. The Field of the Invention
The present invention is related to a piezoelectric device for igniting, or otherwise initiating components within an apparatus, such as a flare or other projectile. More particularly, the present invention is related to a device for converting forces otherwise present in an apparatus, to electricity by means of a piezoelectric cell.
2. Technical Background
In a number of contexts it is necessary to initiate a sequence of events in the operation of a device, which sequence of events may necessarily take place at a location remote from an abundant source of energy, fuel, or other supplies. This is particularly the case in many aerospace and military devices. Such devices must necessary perform a sequence of well defined functions, at precisely specified times, and at a location which is some distance from the point of origin of the device. For example, devices such as missiles, rockets, spacecraft, and many other similar devices essentially become projectiles during normal operation.
In each such device, a series of functions must necessarily be performed at a location remote from the point of origin of the device. In order for a spacecraft to achieve its desired orbit, several rocket motor or booster stages may be used. In addition, it may be necessary at some point to separate the spacecraft itself from the bulk of the rocket motors or boosters. Each stage in the operation of the booster must be initiated at a precise predetermined time in the flight sequence of the device.
Another example is in the deployment of a flare. A number of sophisticated flare designs are known and are used to provide necessary light to a remote area. These flares are generally powered by a rocket motor. When the flare reaches a particular desired location, one or more parachutes are deployed in order to place the flare in the air over the desired location. At the same time, it is necessary to ignite the illuminant material contained within the flare. Each of these functions must be performed at a precise time within the operational sequence of the device. Each of these functions must clearly be initiated at a point remote from the point of origin of the flare and using only mechanical, electrical, and chemical mechanisms contained within the flare itself.
One of the problems encountered in these types of devices is that space is limited. In order to power such devices it is necessary to use a relatively large quantity of fuel in order to achieve the speeds necessary, and to cover the desired distances. At the same time, materials required to perform necessary functions, such as illuminant in the case of the flare, take up a substantial amount of the available space. It is desirable to maximize this type of load. As a result, space within this type of device is at a premium and it is clearly very desirable to provide such devices with mechanisms for initiating necessary functions which are compact to the maximum extent possible.
Reliability is another serious concern. When a device is traveling rapidly toward its destination, it must function properly. If any part of the device fails to operate, the device may become totally ineffective and useless and may also become a serious safety hazard. This is particularly true because in-flight repair or adjustment may be impossible.
As mentioned above, another important consideration is safety. In many of the device described above, highly flammable or explosive materials are used. It is, therefore, important that a mechanism which initiates a function within the device do so only at the appropriate time. If certain functions, such as illumination of a flare, occurred prematurely, such an event would clearly present a serious safety hazard. Thus, great effort is taken to prevent premature or unsafe operation of this type of device.
The present invention teaches the use of a piezoelectric material to provide electrical output for initiation of certain sequences and functions. Piezoelectric materials may be naturally occurring crystalline materials, such as quartz and tourmaline. Alternatively, materials known as polarized piezoelectric ceramics are also available. These are typically referred to as ferroelectric materials. In contrast to naturally occurring piezoelectric crystals, ferroelectric ceramics are of "polycrystalline" structure. Such materials include lead zirconate titanate, barium titanate, lead titanate, and lead metaniobate.
Piezoelectric ceramics and related materials have been used widely in certain contexts. For example, it is known to use a piezoelectric material as an impact detonator for certain types of explosives. The piezoelectric material is placed within the nose of an explosive charge. When the charge impacts on a target, an electrical output is created, which can be used to initiate the explosive material. Similarly, piezoelectric materials have been used as base detonators. That is, they have been placed in the base of a projectile and have been used to detonate an explosive carried by the projectile. Various modifications of this concept have been disclosed.
Piezoelectric ceramics, however, have not typically been used to initiate operating functions other than triggering an explosion. In initiating operating functions within a device it has not been a known concept to use otherwise wasted energy to produce onboard electrical energy. While the energy of impact has been used to produce electrical energy for detonation, other types of functions have not typically been initiated by electrical energy produced during operation of the device.
Accordingly, it would be an advancement in the art to provide an additional mechanism for initiating operational functions within devices such as military and aerospace devices. It would also be an advancement in the art to provide such initiation devices which were at the same time compact, reliable, and safe. It would be another advancement in the art to provide such a device which was able to generate a usable electrical output using energy otherwise produced during normal operation of the device. It would be a further advancement in the art to provide such a device which incorporated piezoelectric generating capability, and which was able to produce sufficient electrical output for the necessary purposes.
Such a device is disclose and claimed herein.